Asked — Edited

Better Servos

Is it possible to use AX-12A Professional Robot servos with the EZ-Robot kit? I'm making a are out to test some ideas and the servos that came with my bot kit are not strong enough. I want to use AX-12A Servos form http://www.trossenrobotics.com/dynamixel-ax-12-robot-actuator.aspx

Is this Possible?


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#1  

Hello rashad , welcome to EZ Robot! Yes you can use dynamixel servos but honestly unless you really need 1024 position resolution instead of rc servos 255 positions then its not worth your trouble. I imagine you still want to know how they work.:) Dynamixel is considered Ferrari of servos so they don't mind making things difficult. Take in mind im not suggesting they are right for you. They use a TTL serial connection. You need to have have a ttl controller for each servo. Each servo will use two digital ports on ezb. Here is a high tech drawing..... (not hardly lol) you need this chip called a tri state buffer.74LS241N http://html.alldatasheet.com/html-pdf/28082/TI/SN74LS241N3/25/1/SN74LS241N3.html

User-inserted image

User-inserted image

Personally given the complications most cases a nice digital servo will do the job for much less work. For cheap servos that are also strong I use 1501mg power hd 26 usd 240oz in torque or ezrobot store high torque servos 133 oz in torque 13 usd. Servos that come with the kit are not heavy duty but I assure you we have plenty of simple solutions to suggest over the complexity of the dynamixel serial drop setups.

#2  

Wow thanks for the great Ideas. This is what I'm making and trying to accomplish using potentiometers from some joystick guts I have. They will allow me to add up to eight pots and 16 buttons. It just seems like my batteries run out fast or my servos do not deliver enough power to run longer than 5 minutes. I want an arm that cost $25 to build insted of $250 by some other company. User-inserted image

United Kingdom
#3  

Are you using the 6 AA cells shown in your photo? That could be why battery life isn't great...

#4  

That's exactly what I'm using @RichMR2. What should I use instead?

#5  

I want to do the same thing they are doing but with my EZ-Robot board and software. I also want to take there products and make lighter versions of them using foam. But more importantly the ability to use Dynamical servos. I wish some body make shield for the EZ-B so we don't have to change the hardware an it fits right in existing pin configuration. I love what EZ B is doing but if we can make it program like Arboitix Controller using the same software or something like it,OMG. Check Out what they are doing.

Projects Using the ArbotiX Controller

just awesome.

United Kingdom
#6  

There are a lot of options for powering the EZB. The FAQ states a 7.2v battery from an RC is ideal, many use 6v or 12v SLA and parallel them to increase the capacity. LiIon cells are another good choice, as are LiFe cells. I personally use a 5000mAh 7.4v LiPo cell but may throw more in to increase time needed between charges.

Basically, you want something with high capacity and between 6v and 12v, or better yet a fixed power supply from an old appliance which can supply between 6v and 17v, I use an old DVD 12v power supply for bench testing which works great. Josh recently posted about using an ATX PSU which would be another good option for bench testing.

#7  

Are you say saying just grab an ATX and plug it right in? That would make sense. My makerbot use one and all of its connections. Also I need something stronger maybe a servo that can turn like 1lb with no issues.

United Kingdom
#8  

https://synthiam.com/Community/Questions/2602 for the ATX PSU info.

As for the servos, I have little idea on that front but I'm sure someone else will come along and chip in.

#9  

I use pololu.com power hd servos for the heaviest loads. They handle 240 oz in torque. You could use servocity.com gearbox to multiply torque. I have the 5 to 1 gear ratio using the pololu servos to get 1200 oz. Of torque.. you can buy just the gearbox kit and use it with your own servo. It costs twice as much to buy it premade.

United Kingdom
#10  

Hello can anyone please tell me if that is possible to achieve position feedback with esb as shown in the dynomixel demo? If so how? Is it posable with encoders? That would be so usefull

#11  

Ezrobot has a different feature called the "record" option. Because rc servos have a pot and control board built inside it doesn't send feedback to the controller. You could mount pots on your joints and use adc ports to read their position but the record function works just as well. :)

#12  

When I get some free time I'm going to have to design an inline pot/ servo holder to fake it. Of course I im going to post the file for everybody who has a 3d printer. I think it would be cool. The only issue is the amount of pots the ez robot allows.

#13  

Lol im amazed at how many people have 3d printers

#14  

What is the strongest servo that is compatible with EZ-B?

#15  

@Jstarne1 I purchased my printer in January 2010. Back then you could Call Bre Pettis up and talk to him directly at Makerbot. I was Makerbot #790. Now you will be lucky if he answers an email he is so busy. They are close to 100,000 bots now.

Spain
#16  

Rashad Hello! any RC servo supports ez-b, if the high torque servo is better to use separate power, personally I like these servos, very strong and cheap:

s8166m

Certainly I like your idea of ??building robot arms with foam, maybe a thin aluminum coating would make it more resistant.

#17  

@R2D2, The R2 stuff is very strong. I lift weights and consider my self a strong brother and one of my Robot arms are unbend-able (almost). I'm going to be using it for all my prototypes from now one. Best of all its not brittle or flaky. I guess that's why they use it for houses because they know it will stand the test of time. I also own a Vinyl cutter put a ball point pen it to make all of my templates. With a Hot wire you make all types of stuff and I don't have to pull out my CNC or 3D Printer.:P By the way IRobot is my favorite movie, I even own the 2004 leather converse and the same leather jackets and pants he wore in the movie. At some point I'm going to purchase a white R8 Audi (God willing). ;)

#19  

For some reason eBay says that item doesn't exist. Why don't you copy the specs and title and past them as auctions only exist for so long.

#20  

I found the manufactures site for those SM-S8166M servos @R2 was speaking of. I couldn't find prices there but all of the specs are available. May be worth looking at. I'm really new to robotics and don't know every technical aspect yet but I see they have 'Robot Servos.' I'm pretty sure I know the difference between analogue and digital servos,(Digi = 1/0's and analogue = Voltage) but what's the deal with these 'Robot Servos'?

http://www.springrc.cn/english/

They seem to make a servo for just about anything you could need.

@Rashad I like your DIY attitude. Good luck with the Audi purchase :)

PRO
Synthiam
#21  

Also keep in mind our heavy duty servos are pretty amazing :)

For the dynamixel servos, that is possible with ezb easily. The ezb is a TTL controller. In fact, it's 20 TTL controllers :)

#22  

Lol 20 ttl . that's good. A feature in ARC for dynamixal would be paramount! Since they have a great following for versatility and reliability. I have a few of the eZ robot high torque servos and they perform like servos you would buy for 40 to 50 dollars at your local hobby shop.

#23  

I have 18 dynamixal servos. I would love to be able to use my EZB to control them. They can be used as regular servos or turn continuous for drive servos. If the EZB could also read the servo position, that would be so cool!

#24  

Speaking of better servos...:) Is it possible to use two servos for one movement and have them "synced up" or would one fight the other? I am thinking of have two servos , an inside and outside for a shoulder joint. I understand one higher torque servo could do the job but having two servos is also a design/art feature for my steampunk robot/animatron FRED... :)

#25  

Many robot arms use two servos for the shoulder joint. So, yes you can do that and make it stronger. Just make sure they are working together and never fight each other.

#26  

@irobot yes you can use two servos on one point of movement but the challenge is that if two servos are aligned perfect they can fight each other when they move and eventually overheat. There are ways to work Arounds. There are trim boxes futuba and hitec make to fine tune their position so they are in sync. Also RC guys who are okay with a tiny bit of wire and soldering can disconnect one of the POT sensors and jumper the servos so they share the same pot and only move together. I've also heard of eliminating one of the control boards and paralleling the output to motor connection to the motor in the second servo. Agian that ensures they will only move together. You could bench test these two methods and see what you like the best.